Multi-speed transmission

ABSTRACT

A transmission is disclosed having an input member, an output member, a plurality of planetary gear sets, a plurality of interconnecting members and a plurality of torque-transmitting mechanisms. The plurality of planetary gear sets has first, second and third members. The input member is continuously interconnected with a member of the planetary gear sets. The output member is continuously interconnected with another member of the planetary gear sets. At least eight forward speeds and one reverse speed are produced by the selective engagement of the five torque-transmitting mechanisms.

CROSS-REFERENCE TO RELATED APPLICATION

The present patent application claims priority to provisional patentapplication No. 60/879,957, filed on Jan. 25, 2007.

TECHNICAL FIELD

The invention relates to a multi-speed transmission having both aplurality of planetary gear sets and torque transmitting devices thatare selectively engageable to achieve multiple gear ratios.

BACKGROUND

A typical multi-speed transmission uses a combination of frictionclutches and planetary gear arrangements to achieve a plurality of gearratios. The number and placement of the planetary gear sets, generally,are dictated by packaging, cost and desired speed ratios.

While conventional transmissions achieve their intended purpose, theneed for new and improved transmission configurations continues with thedesign of lighter and more compact vehicles. Accordingly, there is aneed for a cost-effective, compact and multi-speed transmission.

SUMMARY

A transmission is provided having an input member, an output member, aplurality of planetary gear sets, a plurality of interconnecting membersand a plurality of torque-transmitting mechanisms. The plurality ofplanetary gear sets has first, second and third members. The inputmember is continuously interconnected with the second member of thesecond planetary gear set. The output member is continuouslyinterconnected with the second member of the fourth planetary gear set.A first interconnecting member continuously interconnects the firstmember of the first planetary gear set with the first member of thesecond planetary gear set. A second interconnecting member continuouslyinterconnects the second member of the first planetary gear set with thethird member of the fourth planetary gear set. A third interconnectingmember continuously interconnects the third member of the secondplanetary gear set with the first member of the third planetary gearset. A fourth interconnecting member continuously interconnects thesecond member of the third planetary gear set with a second member ofthe fourth planetary gear set. A first torque-transmitting mechanismselectively interconnects the first member of the first planetary gearset with a stationary member. A second torque-transmitting mechanismselectively interconnects the third member of the first planetary gearset with the stationary member. A third torque-transmitting mechanismselectively interconnecting the second member of the second planetarygear set with the first member of the fourth planetary gear set. Afourth torque-transmitting mechanism selectively interconnects the firstmember of the third planetary gear set with the first member of fourthplanetary gear set. A fifth torque-transmitting mechanism selectivelyinterconnects the third member of the third planetary gear set with thefirst member of the fourth planetary gear set. The torque-transmittingmechanisms are engageable in combinations of at least three to establishat least eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.

In another aspect of the present invention, the first member is a sungear.

In yet another aspect of the present invention, the second member is acarrier member.

In yet another aspect of the present invention, the third member is aring gear.

In yet another aspect of the present invention, the input member iscontinuously connected to the carrier member of the second planetarygear set.

In yet another aspect of the present invention, the output member iscontinuously connected to the carrier member of the fourth planetarygear set.

In yet another aspect of the present invention, the thirdtorque-transmitting mechanism selectively interconnects a carrier memberof the second planetary gear set with a sun gear of the fourth planetarygear set.

In yet another aspect of the present invention, the thirdtorque-transmitting mechanism selectively interconnects the input memberwith a sun gear of the fourth planetary gear set

In yet another aspect of the present invention, the fourthtorque-transmitting mechanism selectively interconnects a sun gear ofthe third planetary gear set with a sun gear of the fourth planetarygear set.

In yet another aspect of the present invention, the fourthtorque-transmitting mechanism selectively interconnects a sun gear ofthe fourth planetary gear set with a sun gear of the third planetarygear set and a ring gear of the second planetary gear set.

In yet another aspect of the present invention, the fifthtorque-transmitting mechanism selectively interconnects a ring gear ofthe third planetary gear set with a sun gear of the fourth planetarygear set.

In yet another aspect of the present invention, the firstinterconnecting member continuously interconnects a sun gear of thefirst planetary gear set with a sun gear of the second planetary gearset.

In yet another aspect of the present invention, the secondinterconnecting member continuously interconnects a carrier member ofthe first planetary gear set with a ring gear of the fourth planetarygear set.

In yet another aspect of the present invention, the thirdinterconnecting member continuously interconnects a ring gear of thesecond planetary gear set with a sun gear of the third planetary gearset.

In yet another aspect of the present invention, the fourthinterconnecting member continuously interconnects a carrier member ofthe third planetary gear set with a carrier member of the fourthplanetary gear set.

In yet another aspect of the present invention, the firsttorque-transmitting mechanism selectively interconnects a sun gear ofthe first planetary gear set with the stationary member.

In yet another aspect of the present invention, the firsttorque-transmitting mechanism selectively interconnects a sun gear ofthe first planetary gear set and a sun of the second planetary gear setwith the stationary member.

In yet another aspect of the present invention, the secondtorque-transmitting mechanism selectively interconnects a ring gear ofthe first planetary gear set with the stationary member.

In still another aspect of the present invention, the selectiveinterconnection created by the first, second and fifthtorque-transmitting mechanisms produce a reverse gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the first, second and thirdtorque-transmitting mechanisms produce a first gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the first, second and fourthtorque-transmitting mechanisms produce a second gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the second, third and fourthtorque-transmitting mechanisms produce a third gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the second, fourth and fifthtorque-transmitting mechanisms produce a fourth gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the second, third and fifthtorque-transmitting mechanisms produce a fifth gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the third, fourth and fifthtorque-transmitting mechanisms produce a sixth gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the first, third and fifthtorque-transmitting mechanisms produce a seventh gear ratio.

In still another aspect of the present invention, the selectiveinterconnection created by the first, fourth and fifthtorque-transmitting mechanisms produce an eighth gear ratio.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an embodiment of a transmissionin accordance with the present invention;

FIG. 2 is a truth table listing the engaged torque-transmittingmechanisms for selected torque ratios achieved by the transmission ofFIG. 1; and

FIG. 3 is a lever diagram of the transmission of FIG. 1 illustrating thepower flow from the input through the gear sets to the output, inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like reference numbers refer to likecomponents, in FIG. 1 a multi-speed transmission 10 is depicted. Thetransmission 10 includes an input member 12 and an output member 14. Inthe present embodiment, input member 12 and output member 14 are shafts,and will be referred to as such. Those skilled in the art willappreciate that the input and output members 12, 14 may be componentsother than shafts. The input shaft 12 is continuously connected to anengine (not shown) or to a turbine of a torque converter (not shown).The output shaft 14 is continuously connected with the final drive unitor transfer case (not shown).

Transmission 10 includes four planetary gear sets 16, 18, 20 and 22. Theplanetary gear sets 16, 18, 20 and 22 are connected between the inputshaft 12 and the output shaft 14. In a preferred embodiment of thepresent invention, planetary gear set 16 is a simple planetary gear setthat includes a sun gear member 24, a ring gear member 26 and a carriermember 28 that rotatably supports a set of pinion gears 30 (only oneshown). Sun gear member 24 is connected for common rotation with firstouter shaft 32 and first intermediate shaft 34. Ring gear member 26 isconnected for common rotation with second outer shaft 36. Pinion gears30 are configured to intermesh with sun gear member 24 and ring gearmember 26. Carrier member 28 is connected for common rotation withsecond intermediate shaft 38.

In a preferred embodiment of the present invention, planetary gear set18 is a simple planetary gear set. More specifically, planetary gear set18 includes a sun gear member 42, a ring gear member 44 and a carriermember 46 that rotatably supports a set of pinion gears 48 (only oneshown). Sun gear member 42 is connected for common rotation with firstintermediate shaft 34. Ring gear member 44 is connected for commonrotation with a third intermediate shaft 50. Carrier member 46 isconnected for common rotation with an input shaft 12. Pinion gears 48are configured to intermesh with both sun gear member 42 and ring gearmember 44.

In a preferred embodiment of the present invention, planetary gear set20 is a simple planetary gear set that includes a sun gear member 52, aring gear member 54 and a carrier member 56 that rotatably supports aset of pinion gears 58 (only one shown). Sun gear member 52 is connectedfor common rotation with a third intermediate shaft 50. Ring gear member54 is connected for common rotation with fourth intermediate shaft 60.Carrier member 56 is connected for common rotation with fifthintermediate shaft 62. Pinion gears 58 are configured to intermesh withboth sun gear member 52 and ring gear member 54.

In a preferred embodiment of the present invention, planetary gear set22 is a simple planetary gear set that includes a sun gear member 72, aring gear member 74 and a carrier member 76 that rotatably supports aset of pinion gears 78 (only one shown). Sun gear member 72 is connectedfor common rotation with sixth intermediate shaft 64 and seventhintermediate shaft 66. Ring gear member 74 is connected for commonrotation with second intermediate shaft 38. Carrier member 76 isconnected for common rotation with an output shaft 14. Pinion gears 78are configured to intermesh with both sun gear member 72 and ring gearmember 74.

The transmission 10 includes a variety of torque-transmitting mechanismsor devices including a first intermediate clutch 80, a secondintermediate clutch 82, a third intermediate clutch 84, a first brake 90and a second brake 92. First intermediate clutch 80 is selectivelyengageable to connect seventh intermediate shaft 66 to carrier member 46and input shaft 12. Second intermediate clutch 82 is selectivelyengagable to connect sixth intermediate shaft 64 to sun gear member 52.Third intermediate clutch 84 is selectively engagable to connect fourthintermediate shaft 60 to sixth intermediate shaft 64. Brake 90 isselectively engageable to connect outer shaft 32 to transmission housing100 to restrict rotation of shaft 32 relative to housing 100. Brake 92is selectively engageable to connect outer shaft 36 to housing 100 torestrict rotation of shaft 36 relative to housing 100.

The transmission 10 is capable of transmitting torque from the inputshaft 12 to the output shaft 14 in at least eight forward torque ratiosand one reverse torque ratio as indicated in the truth table of FIG. 2.Each of the forward torque ratios and the reverse torque ratios isattained by engagement of one or more of the torque-transmittingmechanisms (i.e. first intermediate clutch 80, a second intermediateclutch 82, a third intermediate clutch 84, a brake 90 and a brake 92).Those skilled in the art will readily understand that a different speedratio is associated with each torque ratio. Thus, at least eight forwardspeed ratios and at least one reverse speed ratio may be attained bytransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 2.Of course, other gear ratios are achievable depending on the geardiameter, gear tooth count and gear configuration selected.

A lever diagram 10A is shown in FIG. 3 that is representative oftransmission 10 of FIG. 1, as well as the connections for the clutches80, 82, 84 and brakes 90, 92. The nodes 24A, 26A, 28A, 42A, 44A, 46A,52A, 54A, 56A, 72A, 74A and 76A of the lever diagram 10A represent thegear members 24, 26, 28, 42, 44, 46, 52, 54, 56, 72, 74 and 76 of FIG. 1such that the same numerical designation with the addition of an Asuffix is used to identify the corresponding node. For example, thenodes 24A and 42A shown in FIG. 3 represent sun gears 24 and 42respectively shown in FIG. 1. Other components of FIG. 3 have the samenumbering convention for the corresponding components in FIG. 1.Moreover, the operation or engagement of clutches 80, 82, 84 and brakes90, 92 to establish the various forward and reverse gear speeds will nowbe described with continuing reference to FIGS. 1, 2 and 3.

To establish the reverse torque ratio (Rev), the torque-transmittingmechanisms or clutches are selected as set forth in the table of FIG. 2.As shown in FIG. 2, first and second brakes 90, 92 and thirdintermediate clutch 84 are engaged to achieve the reverse torque ratio(Rev).

In neutral, none of the clutches or brakes are carrying torque. As notedin FIG. 2, in this gear state, the first and second brakes 90 and 92 areengaged but not carrying torque.

A first forward torque ratio (listed as 1^(st) (first gear) in the truthtable of FIG. 2), is achieved by engaging first and second brakes 90 and92 and first intermediate clutch 80. An arrow is provided in FIG. 2 thatemanates from third intermediate clutch 84 that is released and pointsto the clutch that is engaged (clutch 80), when transitioning fromreverse through neutral to first gear.

A subsequent forward torque ratio, indicated as 2^(nd) (second gear) inFIG. 2, is established by engagement of first and second brakes 90, 92and second intermediate clutch 82. The shift from first gear to secondgear occurs as follows: releasing first intermediate clutch 80 andengaging second intermediate clutch 82 while maintaining engagement ofbrakes 90, 92. An arrow is provided in FIG. 2 that emanates from theclutch that is released (clutch 80) and points to the clutch that isengaged (clutch 82).

The subsequent torque ratio, indicated as 3^(rd) (third gear) in thetruth table of FIG. 2, is established by the engagement of second brake92, first and second intermediate clutches 80 and 82. The shift fromsecond gear to third gear occurs as follows: clutch 82 and brake 92remain engaged, brake 90 is released and clutch 80 is engaged. An arrowis provided in FIG. 2 that emanates from the brake that is released(brake 90) and points to the clutch that is engaged (clutch 80).

The next subsequent forward torque ratio, indicated as 4^(th) (fourthgear) in the truth table of FIG. 2, is established with the engagementof second brake 92, second and third intermediate clutches 82, 84. Theshift from third gear to fourth gear is achieved as follows: engagementof clutch 82 and brake 92 are maintained, clutch 80 is released andclutch 84 is engaged. An arrow is provided in FIG. 2 that emanates fromthe clutch that is released (clutch 80) and points to the clutch that isengaged (clutch 84).

A subsequent forward torque ratio indicated as 5^(th) (fifth gear) inFIG. 2, is established with the engagement of second brake 92 and firstand third intermediate clutches 80 and 84. The shift from fourth gear tofifth gear occurs as follows: the engagement of clutch 84 and secondbrake 92 are maintained, clutch 82 is released and clutch 80 is engaged.An arrow is provided in FIG. 2 that emanates from the clutch that isreleased (clutch 82) and points to the clutch that is engaged (clutch80).

A subsequent forward torque ratio indicated as 6^(th) (sixth gear), inthe truth table of FIG. 2, is established with the engagement of first,second and third intermediate clutches 80, 82 and 84. The shift fromfifth gear to sixth gear occurs as follows: the engagement of clutches80 and 84 are maintained, brake 92 is released and clutch 82 is engaged.An arrow is provided in FIG. 2 that emanates from the brake that isreleased (brake 92) and points to the clutch that is engaged (clutch82).

The next subsequent torque ratio, indicated as 7^(th) (seventh gear) inthe truth table of FIG. 2, is established with the engagement of brake90 and first and third intermediate clutches 80, 84. The shift fromsixth gear to seventh gear occurs as follows; the engagement of clutches80 and 84 are maintained, clutch 82 is released and brake 90 is engaged.An arrow is provided in FIG. 2 that emanates from the clutch that isreleased (clutch 82) and points to the brake that is engaged (brake 90).

The next subsequent torque ratio, indicated as 8^(th) (eight gear) inthe truth table of FIG. 2, is established with the engagement of brake90 and second and third intermediate clutches 82, 84. The shift fromseventh gear to eighth gear occurs as follows: the engagement of clutch84 and brake 90 are maintained, clutch 80 is released and clutch 82 isengaged. An arrow is provided in FIG. 2 that emanates from the clutchthat is released (clutch 80) and points to the clutch that is engaged(clutch 82).

The present invention contemplates that downshifts follow the reversesequence of the corresponding upshift (as described above), and severalpower-on skip-shifts that are single-transition are possible (e.g. from1^(st) to 3^(rd)).

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A transmission comprising: an input member; an output member; first, second, third and fourth planetary gear sets each having first, second and third members, wherein the input member is continuously interconnected with the second member of the second planetary gear set, and the output member is continuously interconnected with the second member of the fourth planetary gear set; a first interconnecting member continuously interconnecting the first member of the first planetary gear set with the first member of the second planetary gear set; a second interconnecting member continuously interconnecting the second member of the first planetary gear set with the third member of the fourth planetary gear set; a third interconnecting member continuously interconnecting the third member of the second planetary gear set with the first member of the third planetary gear set; a fourth interconnecting member continuously interconnecting the second member of the third planetary gear set with a second member of the fourth planetary gear set; a first torque-transmitting mechanism selectively engageable to interconnect the first member of the first planetary gear set with a stationary member; a second torque-transmitting mechanism selectively engageable to interconnect the third member of the first planetary gear set with the stationary member; a third torque-transmitting mechanism selectively engageable to interconnect the second member of the second planetary gear set with the first member of the fourth planetary gear set; a fourth torque-transmitting mechanism selectively engageable to interconnect to the first member of the third planetary gear set with the first member of fourth planetary gear set; a fifth torque-transmitting mechanism selectively engageable to interconnect the third member of the third planetary gear set with the first member of the fourth planetary gear set; and wherein the torque-transmitting mechanisms are selectively engageable in combinations of at least three to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.
 2. The transmission of claim 1 wherein the first member is a sun gear.
 3. The transmission of claim 1 wherein the second member is a carrier member.
 4. The transmission of claim 1 wherein the third member is a ring gear.
 5. The transmission of claim 1 wherein the input member is continuously connected to the carrier member of the second planetary gear set.
 6. The transmission of claim 1 wherein the output member is continuously connected to the carrier member of the fourth planetary gear set.
 7. The transmission of claim 1 wherein the third torque-transmitting mechanism selectively interconnects a carrier member of the second planetary gear set with a sun gear of the fourth planetary gear set.
 8. The transmission of claim 1 wherein the third torque-transmitting mechanism selectively interconnects the input member and the carrier member of the second planetary gearset with a sun gear of the fourth planetary gear set.
 9. The transmission of claim 1 wherein the fourth torque-transmitting mechanism selectively interconnects a sun gear of the third planetary gear set with a sun gear of the fourth planetary gear set.
 10. The transmission of claim 1 wherein the fourth torque-transmitting mechanism selectively interconnects a sun gear of the fourth planetary gear set with a sun gear of the third planetary gear set and a ring gear of the second planetary gear set.
 11. The transmission of claim 1 wherein the fifth torque-transmitting mechanism selectively interconnects a ring gear of the third planetary gear set with a sun gear of the fourth planetary gear set.
 12. The transmission of claim 1 wherein the fourth interconnecting member continuously interconnects a carrier member of the third planetary gear set with a carrier member of the fourth planetary gear set.
 13. The transmission of claim 1 wherein the first interconnecting member continuously interconnects a sun gear of the first planetary gear set with a sun gear of the second planetary gear set.
 14. The transmission of claim 1 wherein the second interconnecting member continuously interconnects a carrier member of the first planetary gear set with a ring gear of the fourth planetary gear set.
 15. The transmission of claim 1 wherein the third interconnecting member continuously interconnects a ring gear of the second planetary gear set with a sun gear of the third planetary gear set.
 16. The transmission of claim 1 wherein the first torque-transmitting mechanism selectively interconnects a sun gear of the first planetary gear set with the stationary member.
 17. The transmission of claim 1 wherein the first torque-transmitting mechanism selectively interconnects a sun gear of the first planetary gear set and a sun of the second planetary gear set with the stationary member.
 18. The transmission of claim 1 wherein the second torque-transmitting mechanism selectively interconnects a ring gear of the first planetary gear set with the stationary member.
 19. A transmission comprising: an input member; an output member; first, second, third and fourth planetary gear sets each having a sun gear, a planet gear carrier and a ring gear, wherein the input member is continuously interconnected with the planet carrier of the second planetary gear set, and the output member is continuously interconnected with the planet carrier of the fourth planetary gear set; a first interconnecting member continuously interconnecting the sun gear of the first planetary gear set with the sun gear of the second planetary gear set; a second interconnecting member continuously interconnecting the planet gear carrier of the first planetary gear set with the ring gear of the fourth planetary gear set; a third interconnecting member continuously interconnecting the ring gear of the second planetary gear set with the sun gear of the third planetary gear set; a fourth interconnecting member continuously interconnecting the planet gear carrier of the third planetary gear set with the planet gear carrier of the fourth planetary gear set; a first torque-transmitting mechanism selectively engageable to interconnect the sun gear of the first and second planetary gear sets with a stationary member; a second torque-transmitting mechanism selectively engageable to interconnect the ring gear of the first planetary gear set with the stationary member; a third torque-transmitting mechanism selectively engageable to interconnect the planet gear carrier of the second planetary gear set with the sun gear of the fourth planetary gear set; a fourth torque-transmitting mechanism selectively engageable to interconnect the sun gear of the third planetary gear set with the sun gear of fourth planetary gear set; a fifth torque-transmitting mechanism selectively engageable to interconnect the ring gear of the third planetary gear set with the sun gear of the fourth planetary gear set; and wherein the torque-transmitting mechanisms are selectively engageable in combinations of at least three to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member. 